The invention relates to a superconducting device, comprising                a) an elongated coated conductor, with a substrate and a quenchable superconducting film, wherein the elongated coated conductor has a width W,        b) and an external shunt system, with                    bridge contacts, electrically connected to the superconducting film, and            a resistive member, thermally insulated from the coated conductor and electrically connected to the bridge contacts.                        
Such a superconducting device is known from EP 2 117 056 B1.
Superconducting devices are used in different ways, in particular to transport electric currents, for current conditioning such as in fault current limiters, or for generating high strength magnetic fields.
Superconducting devices comprise a conductor which may, at a temperature below the so called critical temperature Tc, carry an electric current at practically no ohmic losses. In order to achieve said low temperature, the conductor is typically cooled with liquefied gases such as liquid helium. Further, to have a superconducting state, it is also necessary to stay below a critical current density and below a critical magnetic field with the conductor.
When using high temperature superconductor (HTS) materials, e.g. of YBCO material, higher temperatures, current densities and magnetic fields become accessible. HTS material is typically used as a film (or coating) on a normally-conducting or insulating substrate.
A difficulty when employing superconducting devices is the risk of a sudden loss of the superconducting state, also called a quench. If a region of a superconducting film quenches, a high electric current has to pass through the region now normally conducting, what causes a considerable heating of said region. This heating may damage the superconducting material, what is also called a burnout.
Generally, it is desired that a superconducting device can survive a quench, so it can be used again e.g. after recooling of the device. In order to avoid a burnout of the superconducting material, it is known to protect superconducting films with shunt resistance.
EP 2 117 056 B1 discloses an elongated coated conductor, comprising a superconducting film on a substrate, covered by a first metallic member, and electrically connected to a resistive member running in parallel to the elongated conductor via regularly spaced bridge contacts. The resistive member is spaced apart from the elongated conductor, so the resistive member is thermally decoupled from the elongated coated conductor.
In case of a quench in the superconducting film, the major part of the electric current is rerouted around the quenched region through the resistive member, so the current strength through the elongated conductor in the quenched region is reduced. The major heating occurs in the resistive member then, and not in the elongated conductor.
However, even when using such an external shunt system, a burnout of the superconductor film may still occur.
It is the object of the invention to further reduce the risk of a burnout of a superconducting device in case of a quench in its superconducting film.